Theres an awful lot of different types of metal, so it depends what you want to listen to really. If you want to learn about it, then map of metal is a good place to start.Watch the Kerrang channel for current stuff, and sometimes Sky Arts has great documentaries

Rammstein are industrial metal - from the former east germany, they are famed for their pyrotechnics (2 of the band are licensed to do their own). My favourite track of their is Links234

Sabbath are probably the first metal band. Formed in 69 in Birmingham. Paranoid, Warpigs and Sabbath Bloody Sabbath are possibly their biggest songs, but they've put out a lot with a lot of changes of lineup.

Maiden - formed 1975. Used to be famed for their live shows, esp with a character called Eddie who featured on all their album artwork. Biggest track (for me at least) - Run to the Hills, Number of the Beast, Bring your daughter to the slaughter. Lead singer Bruce Dickinson is a qualified commercial pilot. Very much the face of 80's metal back in the day - long wavy hair, studded leather etc

How old? Old school metal you can't fail with- Metallica, iron maiden, megadeth, anthrax and slayer

But it's an odd scene and they're all a bit geeky /snobby about it so it really depends on the genres he likes.

For really heavy late 30s-40s I suggest brutal truth, early carcass and napalm death - if you want more obscure just ask! But this is an acquired taste. For nu metal, well we all cringe a bit at that but you have your Marilyn Manson and System of a Down and slipknot (I actually like these bands) the cringeworthy ones like limp bizkit or murderdolls - I can't reasonably recommend them. Maybe devildriver for something a bit fast

If it's more alt metal from 90s grunge is good place to start and faith no more, ministry and pitch shifter just to top up

Thrash is kinda fun with exodus, sacred reich oh and municipal waste are amazingly fun live and touring soon. Then there's the emo and pop punk & screamo thing but we all pretend that didn't happen.

I would recommend Gorgoroth (Carving a Giant) and Dissection (God of Forbidden Light) they are Norwegian and Swedish respectively and I love them. They were around in the 80s and 90s and are more death/black metal.

This isn't mine, i havent typed it up, i've copied and pasted it from elsewhere:

Genres

Heavy MetalAlso called "traditional metal". This is the most "basic", rock-oriented kind of metal. You can expect a lot of guitar solos, high pitched vocals, and catchy, hook-based songs when you're listening to heavy metal. Some of the most famous metal bands play traditional metal, such as Judas Priest, Iron Maiden, Manowar, and King Diamond.

Doom MetalDoom metal is shockingly hard to pin down. It's debatably the oldest kind of metal, having been invented along with metal itself with Black Sabbath, and the subgenres of it have developed so far from the basic sound that about the only thing you can say about it is that it's slow and heavy. Traditional doom metal bands such as Black Sabbath and Witchfinder General are quite popular, but any metalhead needs to be aware of the representatives of death/doom and funeral doom styles - look for bands such as Evoken, Catacombs, My Dying Bride, and Autopsy.

Thrash MetalThe average listener is probably more familiar with thrash metal than any other genre, as Metallica, Megadeth, Slayer, Anthrax, Testament, and many other extremely well known bands either fall under its umbrella now, or did at some point in their career. Thrash metal is always influenced by punk rock and hardcore to some degree. Common elements include fast tempos and palm-muted, E-string based riffs. The vocals can be either shouted or sung.

Death MetalMainly an evolution of thrash metal. Death metal actually started as just heavier, less melodic thrash metal bands, usually featuring downtuned guitars - check out old albums by Possessed, Death, and Morbid Angel for some good examples of this. These days, death metal has plenty of variety, but the core elements are still amelodic riffing, growled or screamed vocals, and tempos that are either very fast or at least very erratic.

Black MetalI regard black metal as being aesthetically pretty different from the other kinds of metal, and also as one of the hardest genres to pin down in a description. Most black metal nowadays follows the blueprint developed by Norway in the early 90s, meaning look for grainy production, melodic, tremolo picked riffs(tremolo picking is just picking one note over and over very quickly), and "blast beat"-based drumming. Early advocates of this style include Darkthrone, Mayhem, and Emperor. However, like the other genres, there's no shortage of variety.

Progressive Metal"Progressive" is a term used to describe both rock and metal which feature uncommon, even experimental, elements, frequently taking the form of a heightened level of complexity and an emphasis on unique song structures. Expect to hear a lot of odd time signatures and instruments uncommon to metal in this genre as well as its many crossovers with other genres. Prog metal is exemplified by a wide range bands, notably Opeth, Dream Theater, and Fates Warning.

Power MetalPower metal is a point of confusion for plenty of metal listeners, as it's used to describe both classic heavy metal, usually of the heavier variety hailing from the US or Germany, as well as a very different modern offshoot. The modern offshoot(dubbed "euro power metal") is nowadays closely related to progressive metal and features bands such as Rhapsody, Symphony X, and Angra. This brand of theatrical, keyboard-laden, sometimes even orchestrated metal was pioneered by groups such as Edguy and Helloween.

MetalcoreMetalcore is advertised as a combination of heavy metal and hardcore punk(hence "metalcore"), but this can be misleading. Older "metalcore" bands were essentially hardcore punk, but had more metallic - usually meaning more technical - riffing. Look at Integrity and Earth Crisis for examples. Metalcore bands nowadays are indeed influenced by the metalcore bands of old(perhaps not Integrity, but certainly bands such as Hatebreed or Agnostic Front), but mainly in the way they use breakdowns. Metalcore songs usually feature segments where they transition to slower, "chugging" riffs. These are the breakdowns, and they're meant to make the song seem heavier and more intense as a whole. My impression of most metalcore bands, however, is that outside of the breakdowns, the primary influence is Gothenburg-styled melodic death metal, which is itself usually inspired by traditional heavy metal and thrash metal. Expect a lot of "pedal point" riffing in the style of later At the Gates, meaning the riffs are written around the lowest string(E in standard tuning) and involve lots of perfect intervals, 4ths, 5ths, and octaves, off of it. If you aren't familiar with the music theory aspect of this, just listen to At the Gates' Slaughter of the Soul album and compare it to a modern metalcore band such as As I Lay Dying. The similarity will be immediately obvious.

Nu Metal?Nu metal is a touchy subject. Like metalcore and hair metal, it's something of a pariah here. It is not well liked on 235 or, indeed, in underground metal communities in general. Mainstream publications such as All Music Guide and even Wikipedia tend to classify it as a kind of metal, and understandably so, but metal communities rarely acknowledge it as one of metal's many subgenres. The reasons for this are complex.

Firstly, let me briefly discuss why nu metal might be seen as metal. Obviously, it has metal in the name. This argument comes up a lot here. Someone not familiar with the board will post a thread about Disturbed and either get flamed or have their thread deleted due to it being off-topic, and they will complain that, well, it's nu metal. Obviously metal. The logical flaw here is gaping, and to be perfectly honest I don't think I need to address it in detail. I'll just point out that "nu salt" is not table salt, but in fact, a salt substitute.

Stronger arguments involve the actual similarity nu metal has to the "canon" genres of metal. Nu metal tends to be aggressive, and so does metal. Nu metal tends to feature distorted guitars which the songs are often written around, and so does metal. Nu metal tends to have loud, double bass-heavy drumming, and so does metal. In fact, it is reasonable to say that nu metal was influenced, perhaps quite dramatically, by the "groove metal" style which emerged in the early 90s, which is acknowledged, sometimes grudgingly, as truly metal. Look at bands such as Pantera and Testament in their Low era for examples. Though a little late for the craze at the height of its popularity, the nu metal band Damageplan actually formed from the ashes of Pantera. I think this is probably the strongest argument nu metal supporters can make in favor of it being "really" metal.

The most common arguments against it are about the musical features of nu metal. Yes, it does feature guitar-based songs, yes the riffs are distorted, and yes the drums are heavy, but these things, metal fans argue, are common in all kinds of rock music. Nu metal is just too simplistic and structurally similar to rock music to be called a metal genre, and should, in fact, be regarded as hard rock. This is probably correct. One would do well to remember that nu metal being "heavy" does not, in fact, contribute to it being metal; there are probably pop punk bands which have "heavier"(lower or more distorted, in this case) riffs than Deep Purple, but nobody would argue that pop punk is more metal than Deep Purple, because musically pop punk is very different from Deep Purple and other metal.

I myself do not favor these arguments. While I agree that nu metal is musically dissimilar from other metal genres, but I think the stronger, more salient points are cultural and historical. The fact is that nu metal has almost no real connection to metal music whatsoever. It did not "come from" thrash or even groove metal, as some may argue, and never shared a community with any metal community until metalcore became acknowledged as a metal genre, and even that tends to feature a wildly divergent strain of metal fans. There are practically zero aesthetic similarities between any nu metal bands and any true metal bands. Slipknot probably comes the closest of any nu metal band, but they still lack the musical and community connections with real metal, and as such, are not grouped together with it.

Nu metal bands, including Slipknot, Disturbed, Spineshank, Limp Bizkit, Korn, Linkin Park, and System of a Down, are not Metal

If you want some gender balance Nightwish, Within Temptation, Lacuna Coil, Epica, Arch Enemy, Delain and ReVamp are all excellent bands that have female lead singers. I adore Evanescence but wouldn't count them as metal even though HMV seems to. I picked up my music tastes in the early to mid 00s, and that's where it's stayed pretty much.